A visit to your PC repair shop could be swiftly followed by a trip to court and a short stay in your local jail if it harbours any remotely questionable material - whether you knew about it or not.

That, at least, is the fear as the latest confirmed outing for the Dangerous Pictures Act sees one individual prosecuted after a PC engineer spotted potentially unlawful pictures on their PC - and his line manager passed on details to the police.

The case was decided in St Helens Magistrates Court last week, and the defendant, described by District Judge Ian Lomax as having "low social skills", was sentenced to an 18-month supervision order, 24 hours at an attendance centre and costs of £65.

The relative lightness of this sentence is explained as the judge observed that the motivation for this offence, involving just 14 images, was curiosity: no sharing of files or processing had taken place.

This case highlights two interesting aspects of the now active extreme porn law, which makes it a criminal offence merely to possess certain types of imagery.

First, if recent reports from our enforcement sources are correct, the law is now very definitely being used by police to target pictures involving bestiality.

In the previous instance, it appears that it was used in preference to a charge under the Obscene Publications Act. This suggests that it may simply be easier to obtain a conviction under a law that states that depiction of sex with an animal is an offence – rather than asking a jury to determine whether such a picture "tended to deprave or corrupt".

Second, we have yet to see the law being used specifically in respect of "extreme" imagery – which was the initial justification for its passing. Time will tell.

In respect of computer repairs, this case highlights the risks taken every time a computer is handed over for examination. According to lawyer Julian Young, senior partner at Julian Young & Co, there is no obligation on a computer repair person to refer a matter to the police – though he did comment that he believed that such an obligation did exist in respect of photographic processing.

"There is little comeback for anyone reported in this matter," he said. "In English law, the doctrine of 'fruit of the poison tree' does exist – but mostly in respect of police behaviour. For instance, if the police have obtained a warrant to search premises by deception, then evidence found as a result of that search may be ruled inadmissible.

"However, in the case of a computer engineer reporting you or your PC to the police, you are unlikely to have any comeback. If no prosecution follows and you are able to show that the individual was browsing areas that were not relevant to their work – or the referral was motivated by malice – there might be some limited remedy.

"But it would be very difficult to prove."

This was confirmed by lawyers specialising in IT Contract Law: if you hand your computer over for repair, there is an expectation of privacy – but it is very difficult to show that this has been breached, and therefore very difficult to obtain any redress.

We also spoke to a computer engineer working with a large repair firm in South London. They expressed the view that, contrary to popular belief, there was often a need to look at data on a hard drive.

He said: "One of the most common problems we are asked to deal with is data recovery.

"Many trojans will corrupt the Windows partition table. We use data recovery software to scrutinise the hard drive and hopefully fix the problem. However, before we hand the computer back, it is standard practice to look at some images – very briefly – to make sure that the data has been recovered accurately.

"We don’t browse our clients’ computers for fun: but we do look at a range of files to check that we have done the job successfully. If, in the course of that check, I came across something serious – child porn or terror material – I would certainly alert the police."

Whilst in theory this should only be of concern to individuals who habitually surf in areas where they ought not, readers should remember that many porn sites will download all manner of images, sometimes going well beyond the matter originally sought.

The lesson is therefore clear: be careful where you surf. Clean your PC regularly: and take your own back-ups. ®